MEAN HIGH WATER


A project documenting
Sea Level Rise & Flooding in the Lowcountry


01 OVERVIEW ︎︎︎
02 LATEST ︎︎︎   
03 ARCHIVE ︎︎︎
04 RESOURCES ︎︎︎

ABOUT
Mean High Water (MHW) is a project documenting the impacts of sea level rise in and beyond the South Carolina Lowcountry. The title is in reference to the MHW tidal datum defined and maintained by the NOAA Center for Operational Oceanographic Products and Service.

The tides of Charleston Harbor and the Atlantic Ocean are increasingly encroaching into the natural and built environment of Charleston and the Lowcountry. The rate of increase in the number of coastal flood events is alarming. Approximately 45% of all coastal floods observed in Charleston Harbor from 1953 through 2020 have occurred since 2010. An average of 18.8 coastal floods occurred per year in the 1990s. In the 2010s, the annual average was 42.4 coastal floods2, an increase of over 200%.

This project was started by photographer and engineer Jared Bramblett in 2020. It is intended to be an evolving and collaborative documentation of the impacts of rising seas and how communities are adapting to them. If you are interested in participating and submitting to the project, please reach out. All content on this site is copyrighted. If you are interested in using any content, please submit a request.


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CONTACT 
Jared Bramblett
jaredbramblett@gmail.com

All thoughts and opinions presented on this site are solely those of the author and are not necessarily those of any other organizations.

RECORDS & STATISTICS
Charleston Harbor, Cooper River Entrance1

Coastal Floods (>7-ft MLLW)2
1.
2.
3.
4.
5.
89 (2019)
68 (2020)
58 (2015)
55 (2016)
46 (2017)

Major Coastal Floods (>8-ft MLLW)2
1.
2.
3.
4.
5.
7 (2020)
6 (2015)
4 (2019)
3 (2018)
2 (2009, 1947)

Peak Tide Crests (MLLW)3
1.
2.
3.
4.
5.
09/22/1989 - 12.52-ft (Hugo)
08/11/1940 - 10.23-ft (Unnamed)
09/11/2017 - 9.92-ft (Irma)
10/08/2016 - 9.29 (Matthew)
01/01/1987 - 8.81-ft 

22 of the 36 (61%) major flood tides on record have occurred since 2015.3

Statistics current as of 5/31/2021

REFERENCES

1Tidal Benchmark Station - Charleston, Cooper River Entrance, SC - Station ID: 8665530
This is the homepage for the Charleston Tidal Benchmark, which serves as the main tide gauge referenced for tide levels in the Charleston region. The tidal datums (e.g. MLLW, MHW, MHHW) for Charleston are presented here. Lunar tide levels predictions can be found here, and the database of historic tide levels can be accessed here.

2NOAA Coastal Flood Event Database
This is a database maintained by the NOAA Coastal Services Center that tracks coastal flooding in Charleston and Savannah. It is referenced often throughout this site,  particularly when discussing the number of coastal floods that have occurred in Charleston Harbor.

3Advanced Hydrologic Prediction Service, Charleston, SC
Forecasts for water levels at the tidal bench mark based on meteorological predictions are presented here.

A Game of Inches

September 15 & 16, 2020 - Jared Bramblett



We’re in the middle of a ‘king tide’ cycle on the southeast coast, and the tides have been running roughly 1-1.5 feet higher than NOAA predictions (although almost exactly matching the NWS Advanced Hydrologic Prediction Service) in Charleston Harbor. The peaks of the high tides have occured during the evening the past two nights, which allowed me two opportunities to observe and document them. On 9/15, I biked around the Charleston Peninsula, and on 9/16, I remained on Lockwood Drive adjacent to the Ashley River through the peak of the tide.

The behavior of the tides seems to vary with each event, particularly due to the weather and the winds, and the peak tide observed at the Customs House appears to have occured 20 to 30 minutes after the predicted peak. The behavior of the tides also vary among the river systems, with the Ashley River peaking later than the Cooper River right now. The tides peaked at 8.09 and 7.92 feet MLLW on 9/15 and 9/16, respectively. While this may not seem like a substaintial difference (only 0.17-feet), the impacts along the developed land of the Peninsual are significant. Charleston really is a city at sea level, and these king tides show that it’s a game of inches as to the severity of the flooding from these tides. Thankfully, there was no significant rainfall around the peak of these tides.

© 2021